Eye-tracking using a GPU

1. A method of determining a gaze point of an eye watching a visual display controllable by a display signal, the method comprising:

generating a display signal using a graphics card in order for the visual display to produce a screen pattern;

receiving a signal encoding an image of the eye including a corneo-scleral reflection of the screen pattern; and

determining, based on in part the geometry of said corneo-scleral reflection of the screen pattern, a gaze point of the eye,

wherein said determining a gaze point includes utilizing the graphics card as a parallel processor,

wherein the graphics card receives, directly from the imaging device, the signal encoding an image of the eye including a corneo-scleral reflection of the screen pattern, and

wherein said determining a gaze point comprises:

extracting, using the graphics card, one or more image features in said corneo-scleral reflection of the screen pattern; and

comparing, using the graphics card, said one or more image features with the display signal in order to retrieve these in the screen pattern.

2. A method according to claim 1 , further comprising:

illuminating the eye by invisible light from at least one reference illuminator,

wherein:

the image of the eye further includes a glint produced by said at least one reference illuminator; and

said determining a gaze point is further based on the position of the glint.

3. A method according to claim 1 , wherein the image of the eye is received from an imaging device which is synchronized with the visual display and/or a reference illuminator.

4. A method according to claim 2 , wherein the image of the eye is received from an imaging device which is synchronized with the visual display and/or a reference illuminator.

5. A method according to claim 3 or 4 , further comprising:

repeatedly interlacing the screen pattern with a distinctive reference pattern.

6. A method according to claim 1 , wherein said receiving an image comprises decompressing a compressed image format.

7. A computer-readable medium containing instructions which when executed on a general-purpose computer perform the method of claim 1 .

8. A gaze tracking system, comprising:

a visual display controllable by a display signal;

an imaging device adapted to image the face of a viewer of the visual display; and

a graphics card adapted to generate a display signal for causing said visual display to produce a screen pattern,

said system characterized in a gaze-point determining module adapted to use the graphics card as a parallel processor to determine a gaze point of the viewer's eye based on in part the geometry of a corneo-scleral reflection of the screen pattern using an image of the viewer's eye containing said corneo-scleral reflection of the screen pattern, said image being received from the imaging device,

wherein the gaze-point determining module is operable to cause the graphics card to receive, directly from the imaging device, an image of the viewer's eye containing a cornea-scleral reflection of the screen pattern, and

wherein the graphics card is further adapted to:

extract image features in said corneo-scleral reflection of the screen pattern; and

compare said image features with the display signal in order to retrieve these in the screen pattern.

9. A gaze tracking system according to claim 8 , further comprising one or more reference illuminators, each being adapted to emit invisible light in order to produce a glint on a viewer's eye,

wherein the gaze tracking system is adapted to determine a gaze point of the viewer's eye further based on the position of the glint.

10. A gaze tracking system according to claim 9 , wherein said one or more reference illuminators are detachable.

11. A gaze tracking system according to claim 9 , wherein the imaging device is synchronized with the visual display and/or a reference illuminator.

12. A gaze tracking system according to claim 8 , wherein the imaging device is synchronized with the visual display and/or a reference illuminator.

13. A gaze tracking system according to claim 12 or 11 , wherein the graphics card is adapted to repeatedly interlace the screen pattern of the visual display with a distinctive reference pattern.

14. A personal computer system comprising a gaze tracking system according to claim 8 .